Punch block and the method of making it



United States Patent O 3,304,813 PUNCH BLOCK AND THE METHOD F MAKING IT Edward D. Hennigan, River Forest, Ill., assignor to Teletype Corporation, Skokie, Ill., a corporationof Delaware Filed Dec. 5, 1963, Ser. No. 328,214

. 5 Claims. (Cl. 76-107) This invention relates to punch block assemblages for use with selectively operated punches and to the method of manufacturing such punch block assemblages.

Perforators for use in teletypewriter equipment typically employ a punch block 'assemblage of the type depicted in Patent No. 2,308,543, issued yto A. H. Reiber on January 19, 1943, to make intelligence-representing perforations in a tape in permutation code combinations of holes. Since the perforations represent intelligence, the punch pins in such an assemblage must respond quickly and accurately so as faithfully to reproduce a representation of the intelligence fed to the perforator. Such punch pin response necessarily requires that the method of manufacture used to produce the punch pin assemblage meet very exacting manufacturing requirements. The principal diculty involved in the manufacture of such a punch block assemblage is encountered in the forming and locating of the apertures which guide and retain they punch pins. Since the punch pin is guided by two apertures and enters a third aperture located in a die plat-e during the punching of a hole, these three apertures must be accurately made and positioned so that no binding of the punch pin will occur during its punching movement and so that the punch pin will enter the aperture in the die plate producing a clean, sharply sheared hole accurately located in the tape with-out striking the die plate near the wall of the aperture. Previously, such punch assemblages were manufactured by securing a guide plate above and below a genenally inverted, U-shaped casting. Holes were drilled in the upper and lower guide plates and in the die plate. The upper guide plate and die plate were then lapped to size to size in pairs. After lapping, the upper guide plate and die plate had to Ibe kept in pairs. When the lower guide plate and the paired upper guide plate and die plate were assembled, some hand adjustment was lusually necessary to -allow free travel of the punch pins. Obviously, such a customized method of manufacture was time-consuming, tedious, and extremely expensive.

One method suggested for improving the manufacture of punch block assemblages is contained in Patent No. 3,083,604, issued to A. L. Ferren on April 2, 1963, wherein punch pins coated with lubricant are inserted into a punch block and die block; and a casting resin is poured into place to provide a punch pin retaining and guiding means.

It is an object of the present invention to reduce the cost of manufacturing punch block assemblages for perforato-rs while retaining a high degree of quality in the block produced.

Another object of this invention is to provide a simple and inexpensive punch block assemblage an-d a method of manufacturing it that does not require a high degree of skill.

In accordance with the preferred embodiment of the invention, a punch block is provided wherein the punch pin is slidable in a guiding sleeve that is of ya slightly larger inside diameter than the outside diameter of the pin. The punch 'block assemblage is formed -by drilling punch pin guide apertures in a punch block; drilling those apertures at the final punch pin guide location in the punch block slightly larger than the outside Vdiameter of punch pin guiding sleeves; inserting a mandrel and guiding sleeve through each of these larger apertures with each mandrel extending through bot-h of its guide apertures and `an aperture in a die plate; thus, aligning each punch guiding sleeve with respect to the corresponding aperture in the die plate. Thereafter, a casting material is poured into position to surround each punch pin guiding sleeve and to enter the area of excessive clearance between the outside of the sleeve and the inside of the oversize apertures in the punch block. After the casting material has been allowed to set, the mandrels are withdrawn from the apertures in the die block and from the sleeve; and punch pins are inserted in the sleeves.

A more complete understanding of the invention may be obtained from the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. l is an isometric view of the completed punch block assemblage;

FIG. 2 is a fragmentary isometric view of the punch block with a die plate attached to it, the mandrels and punch pin guiding sleeves -being omitted from this view;

FIG. 3 is an enlarged cross-sectio-nal view taken `along line 3-3 in FIG. l in tthe direction of the arrows showing the position of the guiding ysleeve within the punch block and a mandrel within the guiding sleeve instead -of the punch pin shown in FIG. l.

Referring now to the drawings wherein like reference numbers designate the same parts throughout the several views particular reference Ibeing had to FIG. l wherein there is shown a punch block assemblage consisting of a punch block comprising a right side 6, a left side 7, a top 8, and a bottom 9; and a die plate 10 is attached to the punch block with screws 16. Punch pins 17 are inserted through guide lapertures 18 in the bottom 9 of the punch block and up thnough guiding sleeves 19 into -die apertures 20 in the die plate 10.

The positioning of the guiding means for the punch pins is very critical in the manufacture of a punch block; and the punch pin guiding sleeves 19, which are tubes of .any suitable material, are positioned in place by the die apertures 20 in the die plate 10 and then held in place. The actual movement of the punch pin during a punching operation is within the punch pin guiding sleeve 19. To provide adequate clearance, the guiding sleeve must have an inside diameter slightly larger than the punch pin; but too large an inside diameter, that is, too much clearance, would allow too much late-ral movement of the pin and result in a poorly constructed punch. The inside diameter of the punch pin guiding sleeve is preferably .GC02-inch larger than the normal outside diameter of the punch pin plus maximum tolerance. This provides a radial clearance for the punch pin of at least .000l-inch. Such tubes can be manufactured by any suitable method, preferably by a method known as electr'oforming. In the preferred electroforming, process a casing of hard nickel approximately .CD25-inch thick is electroplated onto a rod or mandrel. The plated casing contains an initial compressive stress which permits `the plated coating to be slipped olf of the mandrel as a thin-walled tube with a very accurate inside diameter several millionths of an inch larger than the mandrel diameter.

The punch pins 17 are slidable along their axes within the punch block assemblage, and die plate 10 has a' recess 26 in its bottom surface adjacent the top 8 of the punch block which is deep enough to provide a gap therein between the die plate and the top 8 of the punch block to provide room for insertion of paper tape to be perforated. The punch pins in their normal mode of operation are moved from a position below the top 8 of the punch block upwardly through the tape in recess 26 and into die apertures 20, shearing holes in the paper tape in the shape of the punch pins 17 and their mating die apertures 20. Punch pins 17 are then retracted downwardly and the tape is advanced a predetermined increment for punching another group of holes.

In the preferred method of c-onstructing a punch block assemblage containing sleeves for guiding the punch pins, guide apertures 18, of a suitable dimension to guide the punch pins 17, are drilled in the bottom 9 of the punch block, and apertures 31 are drilled in the top S of the punch block which apertures 31 are slightly larger than the outside diameter of the punch pin guiding sleeves 19. Punch pin guiding lsleeves 19 are slipped over mandrels 33 and the sleeves and mandrels inserted into apertures 31 with the sleeves positioned flush with the surface 27 of top 8 of the punch block as shown in FIG. 3. The lmandrels 33 also extend through guide apertures 18, through guiding sleeves 19, and into die apertures 2i) which are drilled and lapped to dimension in die plate 10 which is secured onto the punch block. The sleeves 19 may first be slipped over mandrels 33 and both then inserted through holes 31. The die plate 10 may then be screwed onto the punch block. Or, the die plate may first be screwed onto the punch block, the sleeves 19 inserted into apertures 31, and then mandrels 33 inserted through apertures 18, sleeves 19, and apertures 20. In manufacturing a punch block `according to the prior art methods, the exact alignment of the three apertures to permit rapid movement of a punch pin from the two apertures in the punch block and into the die apertures was a major expense. It can be seen that in the method described herein the central aperture and guiding surface of the punch pin is placed in its optimum guiding position by the location of the other two. Thus, extending mandrels 33 into die apertures 20 positions each guiding sleeve 19 to an optimum punch pin guiding location. In fabricating a practical punch block assemblage, however, guiding sleeves 19 must be held in this ideal location. To this end the punch block is turned upsidedown and suitable forms are put into place along top 8 of the punch block and a casting material 36, such as the well known epoxy resins, is poured into place. After this resin solidies, it rigidly holds guiding sleeves 19 in their optimum punch pin guiding location. As shown in FIGS. l and 3 suicient resin is poured into the cavity defined by sides 6 and 7 and top 8 and bottom 9 of the punch block to rigidly hold guiding sleeves 19 but not enough resin to touch the mandrels 33. This resin also fills some of the excess space between guiding sleeves 19 and the walls of the apertures 31 as shown in FIG. 3. Each guiding sleeve 19 is thus custom-positioned by its mandrel 33 to guide its associated punch pin 17 into its associated die aperture 20. This obviates the time-consuming and expensive requirement of lapping punch pin guide apertures and die apertures by pairs so that the critical apertures will be aligned. After the resin has set or hardened, the mandrels 33 are removed; and the punch pins, which will be a permanent part of the punch block assemblies, are inserted in their place.

Epoxy resins are Well known in the art and have a high order of utility in a casting operation, such as that employed in the present invention, due to their characteristics of permitting casting at low pressure, possession of good physical properties, especially resistance to shock and abrasion, and possession of good chemical properties particularly as to low solubility in acids `and organic solvents. It will be noted that any resins which exhibit similar general characteristics may be used. Even metal casting material-s may be used so long as they do not have a melting temperature high enough to damage any of the parts with which they come into contact While in the molten state.

Although only one embodiment of the invention is shown in the drawings and described in the foregoing i specification, it will be understood that invention is not limited to the specific embodiment described, but is capable of modification and rearrangement and substitution of parts and elements Without departing from the spirit of the invention.

What is claimed is:

1. The method of making a punch block assemblage using a punch block with an attached die plate, which comprises the steps of:

forming a punch pin receiving aperture in the die plate;

forming an aperture in the punch block aligned with the aperture in the die plate;

disposing a punch pin guiding sleeve within the aperture in the punch block;

inserting a guide mandrel through the punch pin guiding sleeve and the punch pin receiving aperture in the die plate;

surrounding the punch pin guiding sleeve with a casting material to provide a punch pin guiding sleeve retaining means;

removing the mandrel; and

inserting a punch pin in place of the mandrel.

2. The method of making a punch block assemblage having two punch pin guiding areas for guiding a punch pin toward a punch aperture in an associated die plate comprising:

forming a punch pin guiding aperture in the one of said areas which is to be remote from the die plate of a size to accept a punch pin in sliding relation thereto;

forming an aperture in the area to be closely adjacent the die plate, which aperture is of a diameter substantially larger than the outside diameter of a punch pin to be used in the assemblage;

loosely positioning a sleeve in said last-mentioned aperture which sleeve is of an inside diameter such as to snugly but slidably accommodate the aforementioned punch pin and which is of an outside diameter such as to allow an appreciable amount of movement of it within the aperture;

attaching the die plate to the punch block;

inserting a guide mandrel of substantially the same outside diameter as the punch pin to be used in the assemblage through the remote aperture, the sleeve and the die aperture in the die plate;

fixing the sleeve in the location as determined by the mandrel by pouring a casting material around the sleeve and into the space between the outside of the sleeve and the inside of the aperture adjacent the die plate;

removing the mandrel; and

inserting a punch pin in place of the mandrel.

3. The method of making a punch block assemblage including a punch block with a punch-pin-guiding aperture and having an attached die plate with a punch-pinreceiving aperture comprising the steps of:

inserting into the punch-pin-guiding aperture a punchpin-guiding sleeve having a substantially undersized outside dimension relative to the dimension of the aperture;

positioning the punch-pin-guiding sleeve in line with the punch-pin-receiving aperture in the die plate; and securing the punch-pin-guiding sleeve to the punch block.

4. The method of making a punch block assemblage including a punch block with a punch-pin-guiding aperture and having an attached die plate with a punch-pinreceiving aperture comprising the steps of:

inserting into the punch-pin-guiding aperture a punchpin-guiding sleeve;

inserting a guide mandrel through the punch-pinguiding sleeve and the punch-pin-receiving aperture in the die plate;

securing the punch-pin-guiding sleeve to the punch block;

6 removing the mandrel; and securing the punch-pin-guidiug sleeve to the punch inserting a punch pin in place of the mandrel. block- 5. The method of making a punch block assemblage including a punch block with a punch-pin-guiding aper- References Cited by the Exammer ture and having an'attached die plate with a punch-pin- 5 UNITED STATES PATENTS receiving aperture comprising the steps of: Y 2,379,367 6/ 1945 Marchant 83-684 inserting into the punch-pin-guiding aperture a punch- VI-t 29 149 5 en o s p1n-gudng-s1ve 3,083,604 4/1963 Ferren 76-107 X inserting a guide mandrel which may be a punch pm 10 3 161 099 12/1964 Comet 83 588 X through the punch-pineguiding sleeve and the punchpin-receiving aperture in the die plate; and GRANVILLE Y. CUSTER, JR., Primary Examiner. 

1. THE METHOD OF MAKING A PUNCH BLOCK ASSEMBLAGE USING A PUNCH BLOCK WITH AN ATTACHED DIE PLATE, WHICH COMPRISES THE STEPS OF: FORMING A PUNCH PIN RECEIVING APERTURE IN THE DIE PLATE; FORMING AN APERTURE IN THE PUNCH BLOCK ALIGNED WITH THE APERTURE IN THE DIE PLATE; DISPOSING A PUNCH PIN GUIDING SLEEVE WITHIN THE APERTURE IN THE PUNCH BLOCK; INSERTING A GUIDE MANDREL THROUGH THE PUNCH PIN GUIDING SLEEVE AND THE PUNCH PIN RECEIVING APERTURE IN THE DIE PLATE; SURROUNDING THE PUNCH PIN GUIDING SLEEVE WITH A CASTING MATERIAL TO PROVIDE A PUNCH PIN GUIDING SLEEVE RETAINING MEANS; REMOVING THE MANDREL; AND INSERTING A PUNCH PIN IN PLACE OF THE MANDREL. 